The ecteinascidins are exceedingly potent antitumour agents isolated from the marine tunicate Ecteinascidia turbinata. Several ecteinascidins have been reported previously in the patent and scientific literature. See, for example:
U.S. Pat. No. 5,256,663, which describes pharmaceutical compositions comprising matter extracted from the tropical marine invertebrate, Ecteinascidia turbinata, and designated therein as ecteinascidins, and the use of such compositions as antibacterial, anti-viral, and/or antitumour agents in mammals.
U.S. Pat. No. 5,089,273, which describes novel compositions of matter extracted from the tropical marine invertebrate, Ecteinascidia turbinata, and designated therein as ecteinascidins 729, 743, 745, 759A, 759B and 770. These compounds are useful as antibacterial and/or antitumour agents in mammals.
U.S. Pat. No. 5,149,804 which describes Ecteinascidins 722 and 736 (Et's 722 and 736) isolated from the Caribbean tunicate Ecteinascidia turbinata and their structures. Et's 722 and 736 protect mice in vivo at very low concentrations against P388 lymphoma, B16 melanoma, and Lewis lung carcinoma.
U.S. Pat. No. 5,478,932, which describes ecteinascidins isolated from the Caribbean tunicate Ecteinascidia turbinata, which provide in vivo protection against P388 lymphoma, B16 melanoma, M5076 ovarian sarcoma, Lewis lung carcinoma, and the LX-1 human lung and MX-1 human mammary carcinoma xenografts.
U.S. Pat. No. 5,654,426, which describes several ecteinascidins isolated from the Caribbean tunicate Ecteinascidia turbinata, which provide in vivo protection against P388 lymphoma, B16 melanoma, M5076 ovarian sarcoma, Lewis lung carcinoma, and the LX-1 human lung and MX-1 human mammary carcinoma xenografts.
U.S. Pat. No. 5,721,362 which describes a synthetic process for the formation of ecteinascidin compounds and related structures.
U.S. Pat. No. 6,124,292 which describes a series of new ecteinascidin-like compounds.
WO 0177115, WO 0187894 and WO 0187895, which describe new synthetic compounds of the ecteinascidin series, their synthesis and biological properties.
See also: Corey, E. J., J. Am. Chem. Soc., 1996, 118 pp. 9202-9203; Rinehart, et al., Journal of Natural Products, 1990, “Bioactive Compounds from Aquatic and Terrestrial Sources”, vol. 53, pp. 771-792; Rinehart et al., Pure and Appl. Chem., 1990, “Biologically active natural products”, vol 62, pp. 1277-1280; Rinehart, et al., J. Org. Chem., 1990, “Ecteinascidins 729, 743, 745, 759A, 759B, and 770: potent Antitumour Agents from the Caribbean Tunicate Ecteinascidia turninata”, vol. 55, pp. 4512-4515; Wright et al., J. Org. Chem., 1990, “Antitumour Tetrahydroisoquinoline Alkaloids from the Colonial ascidian Ecteinascidia turbinata”, vol. 55, pp. 4508-4512; Sakai et al., Proc. Natl. Acad. Sci. USA 1992, “Additional anitumor ecteinascidins from a Caribbean tunicate: Crystal structures and activities in vivo”, vol. 89, 11456-11460; Science 1994, “Chemical Prospectors Scour the Seas for Promising Drugs”, vol. 266, pp. 1324; Koenig, K. E., “Asymmetric Synthesis”, ed. Morrison, Academic Press, Inc., Orlando, Fla., vol. 5, 1985, p. 71; Barton, et al., J. Chem Soc. Perkin Trans., 1, 1982, “Synthesis and Properties of a Series of Sterically Hindered Guanidine bases”, pp. 2085; Fukuyama et al., J. Am. Chem. Soc., 1982, “Stereocontrolled Total Synthesis of (+)-Saframycin B”, vol. 104, pp. 4957; Fukuyama et al., J. Am. Chem. Soc., 1990, “Total Synthesis of (+)—Saframycin A”, vol. 112, p. 3712; Saito, et al., J. Org. Chem., 1989, “Synthesis of Saframycins. Preparation of a Key tricyclic Lactam Intermediate to Saframycin A”, vol. 54, 5391; Still, et al., J. Org. Chem., 1978, “Rapid Chromatographic Technique for Preparative Separations with Moderate Resolution”, vol. 43, p. 2923; Kofron, W. G.; Baclawski, L. M., J. Org. Chem., 1976, vol. 41, 1879; Guan et al., J. Biomolec. Struc. & Dynam., vol. 10, pp. 793-817 (1993); Shamma et al., “Carbon-13 NMR Shift Assignments of Amines and Alkaloids”, p. 206 (1979); Lown et al., Biochemistry, 21, 419-428 (1982); Zmijewski et al., Chem. Biol. Interactions, 52, 361-375 (1985); Ito, CRC Crit. Rev. Anal. Chem., 17, 65-143 (1986); Rinehart et al., “Topics in Pharmaceutical Sciences 1989”, pp. 613-626, D. D. Breimer, D. J. A. Cromwelin, K. K. Midha, Eds., Amsterdam Medical Press B. V., Noordwijk, The Netherlands (1989); Rinehart et al., “Biological Mass Spectrometry”, 233-258 eds. Burlingame et al., Elsevier Amsterdam (1990); Guan et al., Jour. Biomolec. Struct. & Dynam., vol. 10 pp. 793-817, (1993); Nakagawa et al., J. Amer. Chem. Soc., 111: 2721-2722 (1989); Lichter et al., “Food and Drugs from the Sea Proceedings” (1972), Marine Technology Society, Washington, D.C. 1973, 117-127; Sakai et al., J. Amer. Chem. Soc., 1996, 118, 9017; Garcia-Rocha et al., Brit. J. Cancer, 1996, 73: 875-883; and pommier et al., Biochemistry, 1996, 35: 13303-13309;
In 2000, a hemisynthetic process for the formation of ecteinascidin compounds and related structures such as phthalascidin starting from natural bis(tetrahydroisoquinoline) alkaloids such as the saframycin and safracin antibiotics available from different culture broths was reported; See Manzanares et al., Org. Lett., 2000, “Synthesis of Ecteinascidin ET-743 and Phthalascidin Pt-650 from Cyanosafracin B”, Vol. 2, No 16, pp. 2545-2548; and International Patent Application WO 00 69862.
Ecteinascidin 736 was first discovered by Rinehart and features a tetrahydro-β-carboline unit in place of the tetrahydroisoquinoline unit more usually found in the ecteinascidin compounds isolated from natural sources; See for example Sakai et al., Proc. Natl. Acad. Sci. USA 1992, “Additional antitumor ecteinascidins from a Caribbean tunicate: Crystal structures and activities in vivo”, vol. 89, 11456-11460.

WO 9209607 claims ecteinascidin 736, as well as ecteinascidin 722 with hydrogen in place of methyl on the nitrogen common to rings C and D of ecteinascidin 736 and O-methylecteinascidin 736 with methoxy in place of hydroxy on ring C of ecteinascidin 736.
Despite the positive results obtained in clinical applications in chemotherapy, the search in the field of ecteinascidin compounds is still open to the identification of new compounds with optimal features of cytotoxicity and selectivity toward the tumour and with a reduced systemic toxicity and improved pharmacokinetic properties.